Tens of thousands of San Francisco commuters have probably taken a few moments to ponder this simple statement, which has been posted near the operator’s station of every Muni bus and streetcar since the early 1960s. The message is simultaneously friendly and forbidding, inviting yet indifferent, personable yet coldly professional.

MSR adds that the shirt, “sets clear expectations on the street, in the workplace, or during uncomfortable visits with estranged relatives.” Plus, proceeds from all sales help keep SF’s wonderful vintage streetcars on the rails.